We don't need umbilical mesenchymal stem cells for therapy. While they are not rejected by host they lack capacity to develop except along predetermined line.
People who are buying same from PP must be using them for some other purpose.
Effective therapies employ autologous cell which are reprogrammed to be pluripotent. These cells can differentiate into every kind of tissue.
https://en.wikipedia.org/wiki/Induced_pluripotent_stem_cell
https://www.youtube.com/watch?v=ji023_aQLK8